It Takes Three to Tango: Triangulation Approach to Answer Ranking in Community Question Answering

Proceedings of the 2016 Conference on Empirical Methods in Natural Language Processing, pages 1586–1597, Austin, Texas, November 1-5, 2016. c⃝2016 Association for Computational Linguistics It Takes Three to Tango: Triangulation Approach to Answer Ranking in Community Question Answering Preslav Nakov, Llu´ıs M`arquez and Francisco Guzm´an Arabic Language Technologies Research Group Qatar Computing Research Institute, HBKU {pnakov,lmarquez,fguzman}@qf.org.qa Abstract We address the problem of answering new questions in community forums, by selecting suitable answers to already asked questions. We approach the task as an answer ranking problem, adopting a pairwise neural network architecture that selects which of two compet- ing answers is better. We focus on the util- ity of the three types of similarities occurring in the triangle formed by the original ques- tion, the related question, and an answer to the related comment, which we call relevance, relatedness, and appropriateness. Our pro- posed neural network models the interactions among all input components using syntac- tic and semantic embeddings, lexical match- ing, and domain-specific features. It achieves state-of-the-art results, showing that the three similarities are important and need to be mod- eled together. Our experiments demonstrate that all feature types are relevant, but the most important ones are the lexical similarity fea- tures, the domain-specific features, and the syntactic and semantic embeddings. 1 Introduction In recent years, community Question Answering (cQA) forums, such as StackOverflow, Quora, Qatar Living, etc., have gained a lot of popularity as a source of knowledge and information. These forums typically organize their content in the form of multi- ple topic-oriented question–comment threads, where a question posed by a user is followed by a list of other users’ comments, which intend to answer the question. Many of such on-line forums are not moderated, which often results in (a) noisy and (b) redundant content, as users tend to deviate from the question and start asking new questions or engage in conver- sations, fights, etc. Web forums try to solve problem (a) in various ways, most often by allowing users to up/down- vote answers according to their perceived useful- ness, which makes it easier to retrieve useful an- swers in the future. Unfortunately, this negatively penalizes recent comments, which might be the most relevant and updated ones. This is due to the time it takes for a comment to accumulate votes. Moreover, voting is prone to abuse by forum trolls (Mihaylov et al., 2015; Mihaylov and Nakov, 2016a). Problem (b) is harder to solve, as it requires that users verify that their question has not been asked before, possibly in a slightly different way. This search can be hard, especially for less experienced users as most sites only offer basic search, e.g., a site search by Google. Yet, solving problem (b) automat- ically is important both for site owners, as they want to prevent question duplication as much as possible, and for users, as finding an answer to their ques- tions without posting means immediate satisfaction of their information needs. In this paper, we address the general problem of …

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